I'm building a display controller with a Raspberry Pi. Basically we're trying to control a set of small OLED screens through the SPI interface. All of the OLEDs are tapping off the same MOSI and SCLK pins directly from the Pi with their own CS pins routed through a demux.
My concern is that the Pi's MOSI/SCLK pins won't be able to deliver sufficient current to the MOSI and CLK pins for the OLEDs to register them so I'm considering using a simple BJT with an external PSU and the MOSI and SCLK pins as switches to deliver the signal to the OLEDs.
My question: is the limited current available to the MOSI and SCLK pins a valid concern? And if so, will this switching circuit do the job? I suspect not, since the Vb and Vc are essentially on the same level, but I can't think of another solution to the problem.